1. Field of the Invention
This invention relates to an integral fluid pressure rupturable apparatus, and more particularly, to an integral reverse buckling safety pressure relief apparatus.
2. Description of the Prior Art
Many various safety pressure relief devices of the rupture disk type have been developed. Generally, these devices include a rupture disk supported between a pair of supporting members or flanges which are in turn connected to a relief connection in a vessel or system containing fluid pressure. When the fluid pressure within the vessel or system exceeds the design rupture pressure of the disk, rupture occurs causing fluid pressure to be relieved from the vessel or system. Generally, such heretofore developed and used rupture disk assemblies have been welded, soldered, bolted or otherwise clamped together, and the rupture disks have generally been formed of a thin frangible metal or other material having a concave-convex shape.
For many years after the initial development of safety pressure relief devices of the rupture disk type, and often presently, the concave-convex rupture disk is placed in the pressure relief assembly so that fluid pressure from the vessel or system to be protected is exerted against the concave side of the disk. This arrangement places the disk in tension and in order to prevent premature stress failures in the disk, the operating fluid pressure exerted on the disk, i.e., the normal operation pressure of the vessel or system, must be considerably less than the pressure at which the disk is designed to rupture.
In more recent years, rupture disk assemblies of the so-called "reverse buckling" type have been developed which are capable of operating at 90 percent or more of the pressure at which the disk is designed to rupture. Such assemblies include various parts which are welded, soldered, bolted or otherwise clamped together and include a concave-convex rupture disk positioned in the assembly so that fluid pressure from the system or vessel to be protected is exerted on the convex side of the disk. This results in the disk being placed in compression during operation and allows the normal fluid pressure exerted on the disk to be relatively close to the pressure at which the disk is designed to rupture. Further, reverse buckling rupture disks can withstand pressure fluctuations within the vessel or system over a long period of time without premature failure. Such reverse buckling rupture disk assemblies have heretofore included knife blades upon which the disk impales when reversed by excess fluid pressure, or scores or grooves on a surface of the concave-convex portion of the disk creating lines of weakness therein so that upon reversal, the concave-convex portion tears along the lines of weakness and opens.
In substantially all of the various safety pressure relief devices developed and used heretofore, various parts are assembled and clamped together. In reverse buckling rupture disk assemblies, the rupture disk is often clamped between a pair of special annular members which are in turn clamped between inlet and outlet flanges. Regardless of the particular techniques used for clamping the rupture disk between supporting members, the pressure at which the disk ruptures is often affected and can be changed appreciably by variables in the holding or clamping means. For example, the rupture pressures of reverse buckling rupture disk assemblies which are welded or soldered together are affected by variations in the welding or soldering heat, the speed at which the welding or soldering is accomplished, the force exerted on the rupture disk by the supporting members, etc. The rupture pressure of reverse buckling rupture disks clamped in bolted assemblies are affected and often substantially changed by variations in the flange configuration, the bolting load exerted on the rupture disk, misalignment of the rupture disk within the supporting members, etc. Further, because heretofore used reverse buckling rupture disk assemblies include various parts which are clamped together, the utilization of such devices in high pressure applications has been limited, i.e., to applications wherein the fluid pressure exerted on the rupture disk are below about 2,000 psig. This limitation has generally been due to the fact that a reverse buckling rupture disk designed for a high pressure application must include a relatively thick concave-convex portion connected to an annular flange portion by a transition connection having a large radius. When high pressures are exerted on the disk, unpredictable failure often occurs at the large radius transition connection in that the diameter of the concave-convex portion is reduced as the pressure forces exerted thereon cause the radius portion to roll inward until the disk fails by rolling off the supporting member.
By the present invention, an integral reverse buckling fluid pressure rupturable apparatus is provided which includes only a single part thereby eliminating the problems mentioned above. Further, the apparatus of the present invention is particularly suitable in high pressure applications in that the rupturable portion of the apparatus does not include a large radius transition connection and consequently the heretofore experienced problems of unpredictable failure are obviated.